Silicon Compounds And Methods For Depositing Films Using Same

ABSTRACT

A composition, and chemical vapor deposition method, is provided for producing a dielectric film. A gaseous reagent including the composition is introduced into the reaction chamber in which a substrate is provided. The gaseous reagent includes a silicon precursor that includes a silicon compound according to Formula I as defined herein. Energy is applied to the gaseous reagents in the reaction chamber to induce reaction of the gaseous reagents and to thereby deposit a film on the substrate. The film as deposited is suitable for its intended use without an optional additional cure step applied to the as-deposited film. A method for making the composition is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/717,454 filed Aug. 10, 2018, and U.S. patentapplication Ser. No. 16/532,657 filed Aug. 6, 2019, and is a Divisionalapplication of Ser. No. 16/657,105, filed Aug. 9, 2019, the disclosuresof which are hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

Described herein are compositions and methods for the formation ofdielectric films using silicon compounds as a structure formingprecursor(s). More specifically, described herein are compositions andmethods for forming a low dielectric constant film (“low k” film or filmhaving a dielectric constant of about 3.2 or less), wherein the methodused to deposit the film is a chemical vapor deposition (CVD) method.The low dielectric constant films produced by the compositions andmethods described herein can be used, for example, as insulating layersin electronic devices.

The electronics industry utilizes dielectric materials as insulatinglayers between circuits and components of integrated circuits (IC) andassociated electronic devices. Line dimensions are being reduced inorder to increase the speed and memory storage capability ofmicroelectronic devices (e.g., computer chips). As the line dimensionsdecrease, the insulating requirements for the interlayer dielectric(ILD) become much more rigorous. Shrinking the spacing requires a lowerdielectric constant to minimize the RC time constant, where R is theresistance of the conductive line and C is the capacitance of theinsulating dielectric interlayer. Capacitance (C) is inverselyproportional to spacing and proportional to the dielectric constant (k)of the interlayer dielectric (ILD). Conventional silica (SiO₂) CVDdielectric films produced from SiH₄ or TEOS (Si(OCH₂CH₃)₄,tetraethylorthosilicate) and O₂ have a dielectric constant k greaterthan 4.0. There are several ways in which industry has attempted toproduce silica-based CVD films with lower dielectric constants, the mostsuccessful being the doping of the insulating silicon oxide film withorganic groups providing dielectric constants ranging from about 2.7 toabout 3.5. This organosilica glass is typically deposited as a densefilm (density˜1.5 g/cm³) from an organosilicon precursor, such as amethylsilane or siloxane, and an oxidant, such as O₂ or N₂O.Organosilica glass will herein be referred to as OSG. As the carboncontent of OSG increases, the mechanical strength of the films, such asHardness (H) and Elastic Modulus (EM) of the films, tend to decreaserapidly as the dielectric constant is reduced.

A challenge, which has been recognized in the industry, is that filmswith lower dielectric constants typically have lower mechanicalstrength, which leads to enhanced defects in the narrow pitch films suchas delamination, buckling, increased electromigration such as thatobserved for conductive lines made from copper embedded in dielectricfilms with reduced mechanical properties. Such defects can causepremature breakdown of the dielectric or voiding of the conductivecopper lines causing premature device failure. Carbon depletion in theOSG films can also cause one or more of the following problems: anincrease in the dielectric constant of the film; film etching andfeature bowing during wet cleaning steps; moisture absorption into thefilm due to loss of hydrophobicity, pattern collapse of fine featuresduring the wet clean steps after pattern etch and/or integration issueswhen depositing subsequent layers such as, without limitation, copperdiffusion barriers, for example Ta/TaN or advanced Co or MnN barrierlayers.

Possible solutions to one or more of these problems include using porousOSG films with increased carbon content but that maintain mechanicalstrength. Unfortunately, the relationship between increasing Si-Mecontent typically leads to decreasing mechanical properties, thus thefilms with more Si-Me will negatively impact mechanical strength whichis important for integration.

One solution proposed has been to use ethylene or methylene bridgedalkoxysilanes of the general formulaR_(x)(RO)_(3−x)Si(CH₂)_(y)SiR_(z)(OR)_(3−z) where x=0−3, y=1 or 2,z=0−3. The use of bridged species is believed to avoid the negativeimpact to the mechanical properties by replacing bridging oxygen with abridging carbon chain since the network connectivity will remain thesame. This arises from the belief that replacing bridging oxygen with aterminal methyl group will lower mechanical strength by lowering networkconnectivity. In this manner one can replace an oxygen atom with 1-2carbon atoms to increase the atomic weight percent (%) C withoutlowering mechanical strength. These bridged precursors, however,generally have very high boiling points due to the increased molecularweight from having two silicon groups. The increased boiling point maynegatively impact the manufacturing process by making it difficult todeliver the chemical precursor into the reaction chamber as a gas phasereagent without condensing it in the vapor delivery line or process pumpexhaust.

Thus, there is a need in the art for a dielectric precursor thatprovides a film with increased carbon content upon deposition yet doesnot suffer the above-mentioned drawbacks.

BRIEF SUMMARY OF THE INVENTION

The method and composition described herein fulfill one or more needsdescribed above. The method and composition described herein use atleast one silicon compound(s) such as, for example,2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane or2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane, as a siliconprecursor which can be used as deposited to provide a low-k interlayerdielectric, or can be subsequently treated with thermal, plasma or UVenergy sources to change the film properties to, for example, providechemical crosslinking to enhance mechanical strength. Further the filmsdeposited using the silicon compounds described herein as the siliconprecursor(s) comprise a relatively higher amount of carbon. In addition,the silicon compound(s) described herein have a lower molecular weight(Mw) relative to prior art silicon precursors such as bridgedprecursors, (e.g., alkoxysilaneprecursors) which by nature of having 2silicon groups have a higher MW and higher boiling points, therebymaking the silicon precursors having boiling points 250° C. or less,more preferably 200° C. or less. described herein more convenient toprocess, for example, in a high volume manufacturing process.

Described herein is a single precursor-based dielectric film comprising:a material represented by the formula Si_(v)O_(w)C_(x)H_(y)F_(z), wherev+w+x+y+z=100%, v is from 10 to 35 atomic %, w is from 10 to 65 atomic%, x is from 5 to 45 atomic %, y is from 10 to 50 atomic % and z is from0 to 15 atomic %, wherein the film has pores with a volume porosity of5.0 to 30.0%, a dielectric constant of 2.3 to 3.2 and mechanicalproperties such as hardness of 1.0 to 7.0 Gigapascals (GPa) and elasticmodulus of 4.0 to 40.0 GPa. In certain embodiments, the film comprises ahigher carbon content (10-40%) as measured by X-ray photospectrometry(XPS) and exhibits a decreased depth of carbon removal when exposed to,for example an O₂ or NH₃ plasma as measured by examining the carboncontent determined by XPS depth profiling.

In one aspect, there is provided a chemical vapor deposition method forproducing a dielectric film, comprising: providing a substrate into areaction chamber; introducing gaseous reagents into the reaction chamberwherein the gaseous reagents comprise a silicon precursor comprising ansilicon compound having the structure of Formula I:

wherein R¹ is selected from the group consisting of hydrogen, a linearor branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group; and R² is a C₂ to C₄alkyl di-radical which forms a four-membered, five-membered, orsix-membered saturated cyclic ring with the Si and oxygen atoms withoptional alkyl substituents bonded to the ring, R³ is selected from thegroup consisting of a linear or branched C₁ to C₁₀ alkyl group, a linearor branched C₂ to C₁₀ alkenyl group, a linear or branched C₂ to C₁₀alkynyl group, a C₃ to C₁₀ cyclic alkyl group, a C₃ to C₁₀ hetero-cyclicalkyl group, a C₅ to C₁₀ aryl group, a C₃ to C₁₀ hetero-aryl group, andalkoxy OR⁴ wherein R⁴ is selected from the group consisting of a linearor branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group; at leastone oxygen source, and applying energy to the gaseous reagents in thereaction chamber to induce reaction of the gaseous reagents to deposit afilm on the substrate. The film as deposited is able to be used withoutadditional treatment such as, for example, thermal annealing, plasmaexposure or UV curing.

In another aspect, there is provided a composition for a vapordeposition of a dielectric film comprising a silicon compound having thefollowing Formula I:

wherein R¹ is selected from the group consisting of hydrogen, a linearor branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group; R² is a C₂ to C₄ alkyldi-radical which forms a four-membered, five-membered, or six-memberedsaturated cyclic ring with the Si and oxygen atoms with optional C₁ toC₆ alkyl substituents, R³ is selected from the group consisting of alinear or branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group, and alkoxy OR⁴ wherein R⁴is selected from the group consisting of a linear or branched C₁ to C₁₀alkyl group, a linear or branched C₂ to C₁₀ alkenyl group, and a linearor branched C₂ to C₁₀ alkynyl group.

According to another aspect, the composition is substantially free of atleast one impurity selected from the group consisting of halides,organosilanes, and water.

According to yet another aspect of the invention, a method is providedfor making a silicon compound represented by Formula I:

the method comprising:

-   -   performing hydrosilylation of an alkoxysilane with an        unsaturated alcohol in presence of a catalyst, followed by        cyclization with or without solvent, according to equation (1)        or (2) with yield of 70% higher:

wherein R¹ is selected from the group consisting of hydrogen, a linearor branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group; R³ is selected from thegroup consisting of a linear or branched C₁ to C₁₀ alkyl group, a linearor branched C₂ to C₁₀ alkenyl group, a linear or branched C₂ to C₁₀alkynyl group, a C₃ to C₁₀ cyclic alkyl group, a C₃ to C₁₀ hetero-cyclicalkyl group, a C₅ to C₁₀ aryl group, and a C₃ to C₁₀ hetero-aryl group,and alkoxy OR⁴ wherein R⁴ is selected from the group consisting of alinear or branched C₁ to C₁₀ alkyl group, and a linear or branched C₂ toC₁₀ alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group; andR⁵⁻⁸ are selected from the group consisting of hydrogen, a linear orbranched C₁ to C₁₀ alkyl group.

DETAILED DESCRIPTION OF THE INVENTION

Described herein is a chemical vapor deposition method for producing adielectric film, comprising: providing a substrate into a reactionchamber; introducing gaseous reagents into the reaction chamber whereinthe gaseous reagents comprise a silicon precursor comprising an siliconcompound having the structure of Formula I:

wherein R¹ is selected from the group consisting of hydrogen, a linearor branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group; and R² is a C₂ to C₄alkyl di-radical which forms a four-membered, five-membered, orsix-membered saturated cyclic ring with the Si and oxygen atoms withoptional alkyl substituents bonded to the ring, R³ is selected from thegroup consisting of a linear or branched C₁ to C₁₀ alkyl group, a linearor branched C₂ to C₁₀ alkenyl group, a linear or branched C₂ to C₁₀alkynyl group, a C₃ to C₁₀ cyclic alkyl group, a C₃ to C₁₀ hetero-cyclicalkyl group, a C₅ to C₁₀ aryl group, and a C₃ to C₁₀ hetero-aryl group,and alkoxy OR⁴ wherein R⁴ is selected from the group consisting of alinear or branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, at leastone oxygen source; and applying energy to the gaseous reagents in thereaction chamber to induce reaction of the gaseous reagents to deposit afilm on the substrate. The film can be used as deposited or can besubsequently treated with additional energy selected from the groupconsisting of thermal energy (anneal), plasma exposure, and UV curing tomodify the films chemical properties by increasing the films mechanicalstrength and yielding a dielectric constant less than 3.3.

The silicon compounds described herein provide unique attributes thatmake it possible for one to incorporate more carbon content in thedielectric film with minor impact on the mechanical properties of thelow k dielectric film compared to prior art structure forming precursorssuch as diethoxymethylsilane (DEMS). For example, DEMS has a mixedligand system, which includes two alkoxy groups, one silicon-methyl(Si—Me) and one silicon-hydride which offers a balance of reactive sitesand allows for the formation of more mechanically robust films whileretaining the desired dielectric constant. The use of the siliconcompounds offers the advantages that there are no silicon-methyl groupsin the precursor which tend to lower the mechanical strength, while thecarbon in the silacyclic ring provides carbon to the OSG film to lowerthe dielectric constant and imbue hydrophobicity.

The low k dielectric films are organosilica glass (“OSG”) films ormaterials. Organosilicates are candidates for low k materials. Since thetype of organosilicon precursor has a strong effect upon the filmstructure and composition, it is beneficial to use precursors thatprovide the required film properties to ensure that the addition of theneeded amount of carbon to reach the desired dielectric constant doesnot produce films that are mechanically unsound. The method andcomposition described herein provides the means to generate low kdielectric films that have a desirable balance of electrical andmechanical properties as well as other beneficial film properties ashigh carbon content to provide improved integration plasma damageresistance.

In certain embodiments of the method and composition described herein, alayer of silicon-containing dielectric material is deposited on at aleast a portion of a substrate via a chemical vapor deposition (CVD) orplasma enhanced chemical vapor deposition (PECVD) process, preferably aPECVD process, employing a reaction chamber. Suitable substratesinclude, but are not limited to, semiconductor materials such as galliumarsenide (“GaAs”), silicon, and compositions containing silicon such ascrystalline silicon, polysilicon, amorphous silicon, epitaxial silicon,silicon dioxide (“SiO₂”), silicon glass, silicon nitride, fused silica,glass, quartz, borosilicate glass, and combinations thereof. Othersuitable materials include chromium, molybdenum, and other metalscommonly employed in semi-conductor, integrated circuits, flat paneldisplay, and flexible display applications. The substrate may haveadditional layers such as, for example, silicon, SiO₂, organosilicateglass (OSG), fluorinated silicate glass (FSG), boron carbonitride,silicon carbide, hydrogenated silicon carbide, silicon nitride,hydrogenated silicon nitride, silicon carbonitride, hydrogenated siliconcarbonitride, boronitride, organic-inorganic composite materials,photoresists, organic polymers, porous organic and inorganic materialsand composites, metal oxides such as aluminum oxide, and germaniumoxide. Still further layers can also be germanosilicates,aluminosilicates, copper and aluminum, and diffusion barrier materialssuch as, but not limited to, TiN, Ti(C)N, TaN, Ta(C)N, Ta, W, or WN.

In certain embodiments, the layer of silicon-containing dielectricmaterial is deposited on at least a portion of the substrate byintroducing into the reaction chamber gaseous reagents including atleast one silicon precursor comprising a silicon compound without aporogen precursor. In another embodiments, the layer ofsilicon-containing dielectric material is deposited on at least aportion of the substrate by introducing into the reaction chambergaseous reagents including at least one silicon precursor comprising asilicon compound with a hardening additive.

The method and composition described herein include a silicon compoundhaving the following Formula I:

wherein R¹ is selected from the group consisting of hydrogen, a linearor branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group; and R² is a C₂ to C₄alkyl di-radical which forms a four-membered, five-membered, orsix-membered saturated cyclic ring with the Si and oxygen atoms withoptional alkyl substituents bonded to the ring, R³ is selected from thegroup consisting of a linear or branched C₁ to C₁₀ alkyl group, a linearor branched C₂ to C₁₀ alkenyl group, a linear or branched C₂ to C₁₀alkynyl group, a C₃ to C₁₀ cyclic alkyl group, a C₃ to C₁₀ hetero-cyclicalkyl group, a C₅ to C₁₀ aryl group, and a C₃ to C₁₀ hetero-aryl group,and alkoxy OR⁴ wherein R⁴ is selected from the group consisting of alinear or branched C₁ to C₁₀ alkyl group, a linear or branched C₂ to C₁₀alkenyl group, a linear or branched C₂ to C₁₀ alkynyl group.

In the formula above and throughout the description, the term “alkyl”denotes a linear or branched functional group having from 1 to 10 carbonatoms. Exemplary linear alkyl groups include, but are not limited to,methyl, ethyl, n-propyl, butyl, pentyl, and hexyl groups. Exemplarybranched alkyl groups include, but are not limited to, iso-propyl,iso-butyl, sec-butyl, tert-butyl, iso-pentyl, tert-pentyl, iso-hexyl,and neo-hexyl. In certain embodiments, the alkyl group may have one ormore functional groups attached thereto such as, but not limited to, analkoxy group such as methoxy, ethoxy, iso-propoxy, and n-propoxy, adialkylamino group such as dimethylamino or combinations thereof,attached thereto. In other embodiments, the alkyl group does not haveone or more functional groups attached thereto. The alkyl group may besaturated or, alternatively, unsaturated.

In Formula I above and throughout the description, the term “cyclicalkyl” denotes a cyclic functional group having from 3 to 10 carbonatoms. Exemplary cyclic alkyl groups include, but are not limited to,cyclobutyl, cyclopentyl, cyclohexyl, and cyclooctyl groups.

In Formula I above and throughout the description, the term“hetero-cyclic” denotes a C₃ to C₁₀ hetero-cyclic alkyl group such as anepoxy group.

In Formula I above and throughout the description, the term “alkenylgroup” denotes a group which has one or more carbon-carbon double bondsand has from 2 to 10 or from 2 to 10 or from 2 to 6 carbon atoms.

In Formula I above and throughout the description, the term “alkynylgroup” denotes a group which has one or more carbon-carbon triple bondsand has from 3 to 10 or from 2 to 10 or from 2 to 6 carbon atoms.

In Formula I above and throughout the description, the term “aryl”denotes an aromatic cyclic functional group having from 5 to 10 carbonatoms, or from 6 to 10 carbon atoms. Exemplary aryl groups include, butare not limited to, phenyl, benzyl, chlorobenzyl, tolyl, and o-xylyl.

In Formula I above and throughout the description, the term“hetero-aryl” denotes a C₃ to C₁₀ hetero-cyclic aryl group1,2,3-triazolyl, pyrrrolyl, and furanyl.

In Formula I above, substituent R² is a C₃ to C₁₀ alkyl di-radical whichforms a four-membered, five-membered, or six-membered cyclic ring withthe Si and oxygen atoms. As the skilled person will understand, R² is asubstituted or unsubstituted hydrocarbon chain which links with the Siand oxygen atoms to together form a ring in Formula I wherein the ringis a four-membered, five-membered, or six-membered ring. In theseembodiments, the ring structure may be a saturated ring such as, forexample, a cyclic alkyl ring. Exemplary saturated rings include, but arenot limited to, silacyclobutane, silacyclopentane, and silacyclohexane,preferably silacyclopentane or alkyl such as methyl substitutedsilacylcopentane.

Throughout the description, the term “alkoxy” refers a group derivedfrom an alcohol having at least one carbon atom. Exemplary alkoxy groupsinclude, but are not limited to, methoxy, ethoxy, iso-propoxy,normal-propoxy.

Throughout the description, the term “oxygen source” refers to a gascomprising oxygen (O₂), a mixture of oxygen and helium, a mixture ofoxygen and argon, carbon dioxide, carbon monoxide and combinationthereof.

Throughout the description, the term “dielectric film” refers a filmcomprising silicon and oxygen atoms having composition ofSi_(v)O_(w)C_(x)H_(y)F_(z), where v+w+x+y+z=100%, v is from 10 to 35atomic %, w is from 10 to 65 atomic %, x is from 5 to 40 atomic %, y isfrom 10 to 50 atomic % and z is from 0 to 15 atomic %.

In certain embodiments of Formula I, R¹ is selected from the groupconsisting of hydrogen, methyl, and ethyl; R³ is selected from the groupconsisting of methyl, ethyl, isopropyl, n-propyl, methoxy, ethoxy,iso-propoxy, and n-propoxy; and R² forms a four-membered, five-membered,or six-membered saturated cyclic ring with the Si and oxygen atoms. Insome embodiments, the four-membered, five-membered, or six-memberedsaturated cyclic ring with the Si atom may have at least one alkylsubstituents such as methyl group on the ring structure. Examples ofthese embodiments are as follows:

The silicon compounds having Formula I can be synthesized by, forexample, hydrosilylation of alkoxysilane with unsaturated alcohol inpresence of a catalyst, followed by cyclization to produce1-oxa-2-silacycloalkanes having a five-membered, or six-memberedsaturated cyclic ring with or without solvent (e.g., Equation (1) and(2) with a yield of 70% or higher, preferably 80% of higher. Examples ofsynthesis routess are shown below:

wherein R¹, R³, and R⁴ are same as described aforementioned; R⁵⁻⁸ areselected from the group consisting of hydrogen, a linear or branched C₁to C₁₀ alkyl group, preferably hydrogen or methyl.

The silicon compounds described herein and methods and compositionscomprising same are preferably substantially free of one or moreimpurities such as without limitation, halide ions and water. As usedherein, the term “substantially free” as it relates to each impuritymeans 100 parts per million (ppm) or less, 50 ppm or less, 10 ppm orless, 5 ppm or less, and 1 ppm of less of each impurities such aswithout limitation, chloride or water.

The silicon compounds having Formula I according to the presentinvention and compositions comprising the silicon precursor compoundshaving Formula I according to the present invention are preferablysubstantially free of halide. As used herein, the term “substantiallyfree” as it relates to halide ions (or halides) such as, for example,chlorides (i.e. chloride-containing species such as HCl or siliconcompounds having at least one Si—Cl bond) and fluorides, bromides, andiodides, means less than 5 ppm (by weight) measured by ICP-MS,preferably less than 3 ppm measured by ICP-MS, and more preferably lessthan 1 ppm measured by ICP-MS, and most preferably 0 ppm measured byICP-MS. Chlorides are known to act as decomposition catalysts for thesilicon compounds having Formulae I. Significant levels of chloride inthe final product can cause the silicon precursor compounds to degrade.The gradual degradation of the silicon compounds may directly impact thefilm deposition process making it difficult for the semiconductormanufacturer to meet film specifications. In addition, the shelf-life orstability is negatively impacted by the higher degradation rate of thesilicon compounds having Formulae I thereby making it difficult toguarantee a 1-2 year shelf-life. Therefore, the accelerateddecomposition of the silicon compounds having Formulae I presents safetyand performance concerns related to the formation of these flammableand/or pyrophoric gaseous byproducts. The silicon compounds havingFormula I are preferably substantially free of metal ions such as, Li⁺,Na⁺, K⁺, Mg²⁺, Ca²⁺, Al³⁺, Fe²⁺, Fe²⁺, Fe³⁺, Ni²⁺, Cr³⁺. As used herein,the term “substantially free” as it relates to Li, Na, K, Mg, Ca, Al,Fe, Ni, Cr means less than 5 ppm (by weight), preferably less than 3ppm, and more preferably less than 1 ppm, and most preferably 0.1 ppm asmeasured by ICP-MS. In some embodiments, the silicon compounds havingFormulae I or IA are free of metal ions such as, Li⁺, Na⁺, K⁺, Mg²⁺,Ca²⁺, Al³⁺, Fe²⁺, Fe²⁺, Fe³⁺, Ni²⁺, Cr³⁺. As used herein, the term “freeof” metal impurities as it relates to Li, Na, K, Mg, Ca, Al, Fe, Ni, Cr,noble metal such as volatile Ru or Pt complexes from ruthenium orplatinum catalysts used in the synthesis, means less than 1 ppm,preferably 0.1 ppm (by weight) as measured by ICP-MS or other analyticalmethod for measuring metals. The silicon compounds having Formula I arepreferably also substantially free of water or organosilane impuritiessuch as alkoxysilanes from starting materials or by-products fromsynthesis, as used herein, the term “substantially free” as it relatesto water is less than 100 ppm (by weight), preferably less than 50 ppm,and more preferably less than 10 ppm; the sum of all organosilaneimpurities such as methyltriethyoxysilane or dimethyldiethoxysilaneanalyzed by gas chromatography (GC) is less than 1.0 wt. %, preferablyless than 0.5 wt. %, and preferably less than 0.1 wt. %.

Compositions according to the present invention that are substantiallyfree of halides can be achieved by (1) reducing or eliminating chloridesources during chemical synthesis, and/or (2) implementing an effectivepurification process to remove chloride from the crude product such thatthe final purified product is substantially free of chlorides. Chloridesources may be reduced during synthesis by using reagents that do notcontain halides such as chlorosilanes, bromosilanes, or iodosilanesthereby avoiding the production of by-products that contain halide ions.In addition, the aforementioned reagents should be substantially free ofchloride impurities such that the resulting crude product issubstantially free of chloride impurities. In a similar manner, thesynthesis should not use halide based solvents, catalysts, or solventswhich contain unacceptably high levels of halide contamination. Thecrude product may also be treated by various purification methods torender the final product substantially free of halides such aschlorides. Such methods are well described in the prior art and, mayinclude, but are not limited to, purification processes such asdistillation, or adsorption. Distillation is commonly used to separateimpurities from the desired product by exploiting differences in boilingpoint. Adsorption may also be used to take advantage of the differentialadsorptive properties of the components to effect separation such thatthe final product is substantially free of halide. Adsorbents such as,for example, commercially available MgO—Al₂O₃ blends can be used toremove halides such as chloride.

Whereas prior art silicon-containing silicon precursors such as, forexample DEMS, polymerize once energized in the reaction chamber to forma structure having an —O—linkage (e.g., —Si—O—Si—or —Si—O—C—) in thepolymer backbone, it is believed that a silicon compound having theFormula I polymerizes to form a structure where, some of the —O—bridgein the backbone is replaced with a —CH₂—methylene or —CH₂CH₂—ethylenebridge(s). In films deposited using DEMS as the structure formingprecursor where the carbon exists mainly in the form of terminal Si—Megroups there is a relationship between the % Si—Me (directly related to% C) versus mechanical strength where the replacement of a bridgingSi—O—Si group with two terminal Si—Me groups decreases the mechanicalproperties because the network structure is disrupted. In the case ofthe silicon compounds it is believed that the cyclic structure is brokeneither during the film deposition or the cure process (to remove atleast a portion of, or substantially all, of the porogen precursorcontained in the as-deposited film) to form SiCH₂Si or SiCH₂CH₂Sibridging groups. In this manner, one can incorporate carbon in the formof a bridging group so that, from a mechanical strength view, thenetwork structure is not disrupted by increasing the carbon content inthe film. Without intending to be bound by a particular theory, it isbelieved that this attribute adds carbon to the film, which allows thefilm to be more resilient to carbon depletion of the porous OSG filmfrom processes such as etching of the film, plasma ashing ofphotoresist, and NH₃ plasma treatment of copper surfaces. Carbondepletion in the OSG films can cause increases in the defectivedielectric constant of the film as well as problems with film etchingand feature bowing during wet cleaning steps, and/or integration issueswhen depositing copper diffusion barriers.

In certain embodiments of the method and composition comprised herein,the structure forming precursor further comprises a hardening additivewhich will increase the mechanical strength. Examples of hardeningadditives include tetraalkoxysilanes (Si(OR⁹) wherein R⁹ is selectedfrom the group consisting of a linear or branched C₁ to C₁₀ alkyl group,a linear or branched C₂ to C₁₀ alkenyl group, a linear or branched C₂ toC₁₀ alkynyl group, a C₃ to C₁₀ cyclic alkyl group, a C₃ to C₁₀hetero-cyclic alkyl group, a C₅ to C₁₀ aryl group, and a C₃ to C₁₀hetero-aryl group, such as for example, tetraethoxysilane (TEOS) ortetramethoxysilane (TMOS). In embodiments wherein a hardening additiveis used, the composition of the structure forming portion comprises fromabout 30 to about 95 weight percent structure forming precursorcomprising the alky-alkoxysilacyclic compound(s) having Formula I; fromabout 5 to about 70 weight percent of hardening additive; and about 40to about 95 weight percent of the total precursor flow of porogenprecursor such as alpha terpinene or cyclooctane.

Although the phrase “gaseous reagents” is sometimes used herein todescribe the reagents, the phrase is intended to encompass reagentsdelivered directly as a gas to the reactor, delivered as a vaporizedliquid, a sublimed solid and/or transported by an inert carrier gas intothe reactor.

In addition, the reagents can be carried into the reactor separatelyfrom distinct sources or as a mixture. The reagents can be delivered tothe reactor system by any number of means, preferably using apressurizable stainless steel vessel fitted with the proper valves andfittings to allow the delivery of liquid to the process reactor.

In addition to the structure forming species (i.e., compounds of FormulaI), additional materials can be introduced into the reaction chamberprior to, during and/or after the deposition reaction. Such materialsinclude, e.g., inert gas (e.g., He, Ar, N₂, Kr, Xe, etc., which may beemployed as a carrier gas for lesser volatile precursors and/or whichcan promote the curing of the as-deposited materials and provide a morestable final film) and reactive substances, such as oxygen-containingspecies such as, for example, O₂, O₃, and N₂O, gaseous or liquid organicsubstances, NH₃, H₂, CO₂, or CO. In one particular embodiment, thereaction mixture introduced into the reaction chamber comprises the atleast one oxidant selected from the group consisting of O₂, N₂O, NO,NO₂, CO₂, water, H₂O₂, ozone, and combinations thereof. In analternative embodiment, the reaction mixture does not comprise anoxidant.

Energy is applied to the gaseous reagents to induce the gases to reactand to form the film on the substrate. Such energy can be provided by,e.g., plasma, pulsed plasma, helicon plasma, high density plasma,inductively coupled plasma, remote plasma, hot filament, and thermal(i.e., non-filament) and methods. A secondary rf frequency source can beused to modify the plasma characteristics at the substrate surface.Preferably, the film is formed by plasma enhanced chemical vapordeposition (“PECVD”).

The flow rate for each of the gaseous reagents preferably ranges from 10to 5000 sccm, more preferably from 30 to 1000 sccm, per single 200 mmwafer. The individual rates are selected so as to provide the desiredamounts of silicon, carbon, and oxygen in the film.

The actual flow rates needed may depend upon wafer size and chamberconfiguration, and are in no way limited to 200 mm wafers or singlewafer chambers.

In some embodiments, the film is deposited at a deposition rate of about50 nanometers (nm) per minute.

The pressure in the reaction chamber during deposition ranges from about0.01 to about 600 torr or from about 1 to 15 torr.

The film is preferably deposited to a thickness of 0.002 to 10 microns,although the thickness can be varied as required. The blanket filmdeposited on a non-patterned surface has excellent uniformity, with avariation in thickness of less than 2% over 1 standard deviation acrossthe substrate with a reasonable edge exclusion, wherein, e.g., a 5 mmoutermost edge of the substrate is not included in the statisticalcalculation of uniformity.

Preferred embodiments of the invention provide a thin film materialhaving a low dielectric constant and improved mechanical properties,thermal stability, and chemical resistance (to oxygen, aqueous oxidizingenvironments, etc.) relative to other porous low k dielectric filmsdeposited using other structure forming precursors known in the art. Thestructure forming precursors described herein comprising thealky-alkoxysilacyclic compound(s) having Formula I provide a higherincorporation of carbon into the film (preferably predominantly in theform of organic carbon, —CH_(x), where x is 1 to 3) whereby specificprecursor or network-forming chemicals are used to deposit films. Incertain embodiments, the majority of the hydrogen in the film is bondedto carbon.

The low k dielectric films deposited according to the compositions andmethods described herein comprise: (a) about 10 to about 35 atomic %,more preferably about 20 to about 30 atomic % silicon; (b) about 10 toabout 65 atomic %, more preferably about 20 to about 45 atomic % oxygen;(c) about 10 to about 50 atomic %, more preferably about 15 to about 40atomic % hydrogen; (d) about 5 to about 40 atomic %, more preferablyabout 10 to about 45 atomic % carbon. Films may also contain about 0.1to about 15 atomic %, more preferably about 0.5 to about 7.0 atomic %fluorine, to improve one or more of materials properties. Lesserportions of other elements may also be present in certain films of theinvention. OSG materials are considered to be low k materials as theirdielectric constant is less than that of the standard materialtraditionally used in the industry—silica glass.

Total porosity of the film may be from 0 to 15% or greater dependingupon the process conditions and the desired final film properties. Filmsof the invention preferably have a density of less than 2.3 g/ml, oralternatively, less than 2.0 g/ml or less than 1.8 g/ml. Total porosityof the OSG film can be influenced by post deposition treatment includingexposure to thermal or UV curing, plasma sources. Although the preferredembodiments of this invention do not include the addition of a porogenduring film deposition, porosity can be induced by post depositiontreatment such as UV curing. For example, UV treatment can result inporosity approaching from about 15 to about 20%, with preferably betweenfrom about 5 to about 10%.

Films of the invention may also contain fluorine, in the form ofinorganic fluorine (e.g., Si—F). Fluorine, when present, is preferablycontained in an amount ranging from about 0.5 to about 7 atomic %.

Films of the invention are thermally stable, with good chemicalresistance. In particular, preferred films after anneal have an averageweight loss of less than 1.0 wt %/hr isothermal at 425° C. under N₂.Moreover, the films preferably have an average weight loss of less than1.0 wt %/hr isothermal at 425° C. under air.

The films are suitable for a variety of uses. The films are particularlysuitable for deposition on a semiconductor substrate, and areparticularly suitable for use as, e.g., an insulation layer, aninterlayer dielectric layer and/or an inter-metal dielectric layer. Thefilms can form a conformal coating. The mechanical properties exhibitedby these films make them particularly suitable for use in Al subtractivetechnology and Cu damascene or dual damascene technology.

The films are compatible with chemical mechanical planarization (CMP)and anisotropic etching, and are capable of adhering to a variety ofmaterials, such as silicon, SiO₂, Si₃N₄, OSG, FSG, silicon carbide,hydrogenated silicon carbide, silicon nitride, hydrogenated siliconnitride, silicon carbonitride, hydrogenated silicon carbonitride,boronitride, antireflective coatings, photoresists, organic polymers,porous organic and inorganic materials, metals such as copper andaluminum, and diffusion barrier layers such as but not limited to TiN,Ti(C)N TaN, Ta(C)N, Ta, W, WN or W(C)N. The films are preferably capableof adhering to at least one of the foregoing materials sufficiently topass a conventional pull test, such as ASTM D3359-95a tape pull test. Asample is considered to have passed the test if there is no discernibleremoval of film.

Thus in certain embodiments, the film is an insulation layer, aninterlayer dielectric layer, an inter-metal dielectric layer, a cappinglayer, a chemical-mechanical planarization (CMP) or etch stop layer, abarrier layer or an adhesion layer in an integrated circuit.

Although the films described herein are uniformly deposited dielectricfilms, the films as used in a full integration structure may actuallyconsist of several sandwiched layers with for example a thin layer atthe bottom or top which contains little or no porogen being deposited,or a layer may be deposited under conditions where there is a lowerporogen precursor flow ratio alternatively for example a layer may bedeposited at higher plasma power such that not all the porogen precursorcan be removed by UV treatment. These sandwich layers may be utilized toenhance secondary integration properties such as for example adhesion,etch selectivity or electromigration performance.

Although the invention is particularly suitable for providing films andproducts of the invention are largely described herein as films, theinvention is not limited thereto. Products of the invention can beprovided in any form capable of being deposited by CVD, such ascoatings, multilaminar assemblies, and other types of objects that arenot necessarily planar or thin, and a multitude of objects notnecessarily used in integrated circuits. Preferably, the substrate is asemiconductor.

In addition to the inventive OSG products, the present disclosureincludes the process by which the products are made, methods of usingthe products and compounds and compositions useful for preparing theproducts. For example, a process for making an integrated circuit on asemiconductor device is disclosed in U.S. Pat. No. 6,583,049, which isherein incorporated by reference.

Compositions of the invention can further comprise, e.g., at least onepressurizable vessel (preferably of stainless steel) fitted with theproper valves and fittings to allow the delivery of hardening additiveand the silicon precursor having Formula I such as DESCAP to the processreactor. The contents of the vessel(s) can be premixed. Alternatively,for example hardening additive and precursor can be maintained inseparate vessels or in a single vessel having separation means formaintaining the hardening additive and precursor separate duringstorage. Such vessels can also have means for mixing the porogen andprecursor when desired.

The preliminary (or as-deposited) film can be further treated by acuring step, i.e., applying an additional energy source to the film,which can comprise thermal annealing, chemical treatment, in-situ orremote plasma treating, photocuring (e.g., UV) and/or microwaving. Otherin-situ or post-deposition treatments may be used to enhance materialproperties like hardness, stability (to shrinkage, to air exposure, toetching, to wet etching, etc.), integrity, uniformity and adhesion.Thus, the term “post-treating” as used herein denotes treating the filmwith energy (e.g., thermal, plasma, photon, electron, microwave, etc.)or chemicals to remove porogens and, optionally, to enhance materialsproperties.

The conditions under which post-treating are conducted can vary greatly.For example, post-treating can be conducted under high pressure or undera vacuum ambient.

UV annealing is a preferred method of curing and is typically conductedunder the following conditions.

The environment can be inert (e.g., nitrogen, CO₂, noble gases (He, Ar,Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygenenvironments, enriched oxygen environments, ozone, nitrous oxide, etc.)or reducing (dilute or concentrated hydrogen, hydrocarbons (saturated,unsaturated, linear or branched, aromatics), etc.). The pressure ispreferably about 1 Torr to about 1000 Torr, more preferably atmosphericpressure. However, a vacuum ambient is also possible for thermalannealing as well as any other post-treating means. The temperature ispreferably 200-500° C., and the temperature ramp rate is from 0.1 to 100deg ° C./min. The total UV annealing time is preferably from 0.01 min to12 hours.

Chemical treatment of the OSG film is conducted under the followingconditions.

The use of fluorinating (HF, SIF₄, NF₃, F₂, CO₂F₂, etc.), oxidizing(H₂O₂, O₃, etc.), chemical drying, methylating, or other chemicaltreatments that enhance the properties of the final material. Chemicalsused in such treatments can be in solid, liquid, gaseous and/orsupercritical fluid states.

Supercritical fluid post-treatment for selective removal of porogensfrom an organosilicate film is conducted under the following conditions.

The fluid can be carbon dioxide, water, nitrous oxide, ethylene, SF₆,and/or other types of chemicals. Other chemicals can be added to thesupercritical fluid to enhance the process. The chemicals can be inert(e.g., nitrogen, CO₂, noble gases (He, Ar, Ne, Kr, Xe), etc.), oxidizing(e.g., oxygen, ozone, nitrous oxide, etc.), or reducing (e.g., dilute orconcentrated hydrocarbons, hydrogen, a plasma comprising hydrogen etc.).The temperature is preferably ambient to 500° C. The chemicals can alsoinclude larger chemical species such as surfactants. The total exposuretime is preferably from 0.01 min to 12 hours.

Plasma treating for selective removal of labile groups and possiblechemical modification of the OSG film is conducted under the followingconditions.

The environment can be inert (nitrogen, CO₂, noble gases (He, Ar, Ne,Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygenenvironments, enriched oxygen environments, ozone, nitrous oxide, etc.),or reducing (e.g., dilute or concentrated hydrogen, hydrocarbons(saturated, unsaturated, linear or branched, aromatics), etc.). Theplasma power is preferably 0-5000 W. The temperature is preferably fromabout ambient to about 500° C. The pressure is preferably 10 mtorr toatmospheric pressure. The total curing time is preferably 0.01 min to 12hours.

UV curing for chemical cross-linking of organosilicate film is typicallyconducted under the following conditions.

The environment can be inert (e.g., nitrogen, CO₂, noble gases (He, Ar,Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygenenvironments, enriched oxygen environments, ozone, nitrous oxide, etc.),or reducing (e.g., dilute or concentrated hydrocarbons, hydrogen, etc.).The temperature is preferably from about ambient to about 500° C. Thepower is preferably from 0 to about 5000 W. The wavelength is preferablyIR, visible, UV or deep UV (wavelengths<200 nm). The total UV curingtime is preferably 0.01 min to 12 hours.

Microwave post-treatment of organosilicate film is typically conductedunder the following conditions.

The environment can be inert (e.g., nitrogen, CO₂, noble gases (He, Ar,Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygenenvironments, enriched oxygen environments, ozone, nitrous oxide, etc.),or reducing (e.g., dilute or concentrated hydrocarbons, hydrogen, etc.).The temperature is preferably from about ambient to about 500° C. Thepower and wavelengths are varied and tunable to specific bonds. Thetotal curing time is preferably from 0.01 min to 12 hours.

Electron beam post-treatment for selective removal of porogens orspecific chemical species from an organosilicate film and/or improvementof film properties is typically conducted under the followingconditions.

The environment can be vacuum, inert (e.g., nitrogen, CO₂, noble gases(He, Ar, Ne, Kr, Xe), etc.), oxidizing (e.g., oxygen, air, dilute oxygenenvironments, enriched oxygen environments, ozone, nitrous oxide, etc.),or reducing (e.g., dilute or concentrated hydrocarbons, hydrogen, etc.).The temperature is preferably ambient to 500° C. The electron densityand energy can be varied and tunable to specific bonds. The total curingtime is preferably from 0.001 min to 12 hours, and may be continuous orpulsed. Additional guidance regarding the general use of electron beamsis available in publications such as: S. Chattopadhyay et al., Journalof Materials Science, 36 (2001) 4323-4330; G. Kloster et al.,Proceedings of IITC, Jun. 3-5, 2002, SF, CA; and U.S. Pat. Nos.6,207,555 B1, 6,204,201 B1 and 6,132,814 A1. The use of electron beamtreatment may provide for porogen removal and enhancement of filmmechanical properties through bond-formation processes in matrix.

The invention will be illustrated in more detail with reference to thefollowing Examples, but it should be understood that the invention isnot deemed to be limited thereto.

Working Example 1

Synthesis of 2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane whereinR¹=Me, R³=OEt, R⁴=Et, R⁵=R⁶=Me in eq (1)

To 1.50 mL of Karstedt's catalyst (2% Pt in xylene) in 741.0 g (8.6 mol)2-methyl-3-buten-2-ol heated to 50° C. in a three-neck round bottomflask equipped with an internal thermocouple and reflux condenser wasadded 1155.0 g (8.6 mol) diethoxymethylsilane drop-wise via anadditional funnel. There was an exotherm and the temperature of themixture gradually increased to 85° C. where upon the heating was shutoff. The temperature was maintained between 75-85° C. while addition ofDEMS was carried out. Once addition was complete, the reaction wasallowed to cool back to room temperature and left to stir over night.Ethanol by-product was removed by distillation at ambient pressure andheating up to a vapor temperature of 153° C. The product was vacuumdistilled under 105-108 Torr pressure at 93-94° C. in the amount of 1235g at 97% purity. The yield was 82%.

Working Example 2

Synthesis of 2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane whereinR¹=R³=Me, R⁴=Et, R⁵ =R⁶=Me in eq (1)

To 2.00mL of Karstedt's catalyst (2% Pt in xylene) in 1731.0 g (20.1mol) 2-methyl-3-buten ol heated to 50° C. in a three-neck round bottomflask equipped with an internal thermocouple and reflux condenser wasadded 2095.0 g (20.1 mol) dimethylethoxysilane drop-wise via anadditional funnel. There was a gradual exotherm and the temperature ofreaction reached 87° C. after which the temperature gradually decreasedto 60° C. Addition of DMES was increased whereupon the temperature beganto gradually rise, then there was a sharp exotherm and the reactionmixture refluxed at 95° C. The second temperature spike was more intensethan the first. After addition was complete, the reaction was cooled toroom temperature and stirred over the course of the night. A sample wasrun GC and showed a 3:1 ratio of product to diethoxydimethylsilane.Distillation was carried out at ambient pressure to remove ethanol andresidual 2-methyl-3-buten-2-ol starting material. Removal was ceasedonce the vapor temperature reached 107° C. The product was distilledunder ambient pressure in the amount of 566 g at 97% purity. The yieldwas 20%.

Working Example 3

Synthesis of 2,5,5-trimethyl-2-isopropyl-1-oxa-2-silacyclopentanewherein R¹=Me, R³=iso-propyl, R⁴=Et, R⁵=R⁶=Me in eq (1)

To a one-neck round-bottom flask containing 24.6 g (186.0 mmol)isopropylethoxymethylsilane in 350 mL mixture of hexanes and THF wasadded 16.0 g (186.0 mmol) of 2-methyl-3-buten-2-ol followed by 0.03 mLof Karstedt's catalyst (2% Pt in xylene). The reaction was stirred overthe course of the night. GC-MS indicated evidence of desired product atm/z 172.

Working Example 4 (Film Example)

PECVD of silicon-containing dielectric film using dielectric2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane

Exemplary films for 300 mm wafer processing were formed via a plasmaenhanced CVD (PECVD) process using an Applied Materials Producer SEsystem which deposits films on two wafers at the same time. Thus theprecursor and gas flow rates correspond to the flow rates required todeposit films on two wafers at the same time. The stated RF power perwafer is correct, as each wafer processing station has its ownindependent RF power supply. Films from two different chemicalprecursors under differing process conditions were deposited. The PECVDprocess generally involved the following basic steps: initial set-up andstabilization of gas flows, deposition of the film onto the siliconwafer substrate, and purge/evacuation of chamber prior to substrateremoval. The experiments were conducted on p-type Si wafers (resistivityrange=8-12 Ohm-cm).

Thickness and refractive index were measured on an SCI FilmTek 2000Reflectometer. Dielectric constants were determined using Hg probetechnique on mid-resistivity p-type wafers (range 8-12 ohm-cm).Mechanical properties (elastic modulus and hardness, GPa) weredetermined using nanoindentation techniques, carbon content wasdetermined by X-ray Photoelectron Spectroscopy (atomic %), and thecomposition of species within the SiO_(x) network were determined byinfrared spectroscopy. The latter included the silicon methyl densityattributable to Si(CH₃)₁ and the disilylmethylene bridge density(SiCH₂Si/SiO_(x)*1E4).

Working Example 5 (Film Example)

Low dielectric constant films were deposited using2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane precursor under thefollowing conditions: The total precursor flow rate was 2000 mg/min;oxygen flow rate was 15 sccm; deposition temperature was maintained at390° C.; RF power was varied from 230-500 W; pressure was maintained at7.5 torr; electrode spacing was maintained at 380 mils; He carrier flowused to deliver precursor to the process chamber was 1500 sccm. Table 1below shows the film properties obtained from2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane precursor at threedifferent RF powers. The deposited films exhibited higher mechanicalstrength, higher dielectric constant, and higher network carbon asindicated by the increase in Si—CH₂—Si/SiO_(x) ratio, obtained from theratio of integrated Si—CH₂—Si band to the integrated Si—O band in theFTIR spectra. Incorporating higher network carbon density, such asSi—CH₂—Si, is desirable as it reduces the depth of film damage occurringduring subsequent integration steps, such as etching, ashing,planarization and metalization.

TABLE 1 Film properties obtained from2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane precursor at three RFpowers: Power EM Hardness % Si-CH₂- Si- (W) k (GPa) (GPa) C Si/SiO × 10⁴CH₃/SiO × 10² 230 2.9 14.0 2.0 18 10 2.8 350 3.0 16.4 2.7 24 17 3.0 5003.1 16.4 2.7 28 23 3.2

Working Example 6 (Film Example)

PECVD of silicon-containing dielectric film using dielectric using2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane

Low dielectric constant films were deposited using2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane precursor under thefollowing conditions: The total precursor flow rate was varied form2000-2500 mg/min; oxygen flow rate was 25-50 sccm; depositiontemperature was maintained at 390° C.; RF power was varied from 315-515W; pressure was maintained at 7.5 torr; electrode spacing was maintainedat 380 mils; He carrier flow used to deliver precursor to the processchamber was 1500 sccm. Table 2 below shows the film properties obtainedfrom 2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane precursor atthree different process conditions. The deposited films exhibitedsimiliar mechanical strength and dielectric constants relative to the2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane, but lower network carbonas indicated by the decrease in Si—CH₂—Si/SiO_(x) ratio, obtained fromthe ratio of integrated Si—CH₂—Si band to the integrated Si—O band inthe FTIR spectra. The substitution of a methyl group with an ethoxygroup reduced the quantity of network carbon that could be incorporatedin the film.

TABLE 2 Film properties obtained from 2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane precursor at three RF powers: O₂ Precursor Hard-Si-CH₂- Si- Power Flow Flow EM ness % Si/ CH₃/ (W) (sccm) (mg/min) k(GPa) (GPa) C SiO × 10⁴ SiO × 10² 315 50 2000 2.9 13.1 1.9 16 3.9 3.1415 25 2500 3.0 16.0 2.3 15 5.0 2.5 515 50 2000 3.1 17.0 2.5 15 6.4 2.3

Although illustrated and described above with reference to certainspecific embodiments and examples, the present invention is neverthelessnot intended to be limited to the details shown. Rather, variousmodifications may be made in the details within the scope and range ofequivalents of the claims and without departing from the spirit of theinvention. It is expressly intended, for example, that all rangesbroadly recited in this document include within their scope all narrowerranges which fall within the broader ranges.

1. A method for making a silicon compound represented by Formula I:

the method comprising: performing hydrosilylation of an alkoxysilanewith an unsaturated alcohol in presence of a catalyst, followed bycyclization with or without solvent according to equation (1) or (2):

wherein R¹ is selected from the group consisting of hydrogen, a linearC₁ to C₁₀ alkyl group, a branched C₃ to C₁₀ alkyl group, a linear C₂ toC₁₀ alkenyl group, a branched C₃ to C₁₀ alkenyl group, a linear C₂ toC₁₀ alkynyl group, a branched C₄ to C₁₀ alkynyl group, a C₃ to C₁₀cyclic alkyl group, a C₃ to C₁₀ hetero-cyclic alkyl group, a C₅ to C₁₀aryl group, and a C₃ to C₁₀ hetero-aryl group; R³ is selected from thegroup consisting of a linear C₁ to C₁₀ alkyl group, a branched C₃ to C₁₀alkyl group, a linear C₂ to C₁₀ alkenyl group, a branched C₃ to C₁₀alkenyl group, a linear C₂ to C₁₀ alkynyl group, a branched C₄ to C₁₀alkynyl group, a C₃ to C₁₀ cyclic alkyl group, a C₃ to C₁₀ hetero-cyclicalkyl group, a C₅ to C₁₀ aryl group, and a C₃ to C₁₀ hetero-aryl group,and alkoxy OR⁴ wherein R⁴ is selected from the group consisting of alinear C₁ to C₁₀ alkyl group, a branched C₃ to C₁₀ alkyl group, a linearC₂ to C₁₀ alkenyl group, a branched C₃ to C₁₀ alkenyl group, a linear C₂to C₁₀ alkynyl group and a branched C₄ to C₁₀ alkynyl group; and R⁵⁻⁸are independently selected from the group consisting of hydrogen, alinear C₁ to C₁₀ alkyl group and a branched C₃ to C₁₀ alkyl group. 2.The method of claim 1, wherein the compound represented by Formula I isselected from the group consisting of2,2,5,5-tetramethyl-1-oxa-2-silacyclopentane,2,5,5-trimethyl-2-ethoxy-1-oxa-2-silacyclopentane,2,5,5-trimethyl-2-methoxy-1-oxa-2-silacyclopentane, 2,5,5-trimethyl-2-iso-propoxy-1-oxa-2-silacylopentane,2,2-dimethyl-1-oxa-2-silacyclohexane,2,2,6,6-tetramethyl-1-oxa-2-silacyclohexane,2-methyl-2-ethoxy-1-oxa-2-silacyclohexane,2,6,6-trimethyl-2-ethoxy-1-oxa-2-silacyclohexane,2-methyl-2-methoxy-1-oxa-2-silacyclohexane,2,6,6-trimethyl-2-methoxy-1-oxa-2-silacyclohexane,2-methyl-2-n-propoxy-1-oxa-2-silacyclohexane,2,6,6-trimethyl-2-n-propoxy-1-oxa-2-silacyclohexane,2-methyl-2-iso-propoxy-1-oxa-2-silacyclohexane,2,6,6-trimethyl-2-iso-propoxy-1-oxa-2-silacyclohexane,2,5,5-trimethyl-2-iso-propyl-1-oxa-2-silacyclopentane,2-methyl-2-iso-propyl-1-oxa-2-silacyclopentane,2-methyl-2-iso-propyl-1-oxa-2-silacyclohexane,2,6,6-trimethyl-2-iso-propyl-1-oxa-2-silacyclohexane, and combinationsthereof.